Electromagnet



C. E. AVERY, ELECTROMA'GNET.

APPLICATION FILED IULYIO. 19H.

Patented Apr. 18, 1922.

2 SHEETS-SHEET I.

4 TTUH/VEYS.

C. E. AVERY;v

ELECTROMAGNET. APPLICATION F|LED1JLY10.1911.

Patented Apr. 18, 1922.

UNITED STATES PATENT OFFICE.

CHARLES E. AVERY, OF TRENTON, NEW JERSEY, ASSIGNOR TO MANHATTAN ELEC-TRICAL SUPPLY COMPANY, IN C., OF JERSEY CITY, NEW JERSEY, A CORPGRATION0E MASSACHUSETTS.

Application filed July 10,

To all whom t may concern.'

Be it known that I, CHARLES E. AVERY, a citizen of the United States ofAmerica, and residing in Trenton, in the county of Mercer and State ofNew Jersey, have invented a certain new and useful Improve ment inElectromagnets, of which the following is a specification.

My invention relates to electro-magnets and particularly to alternatingcurrent magnets, the 4object of my invention being to construct a magnetwith an armature, the vibrations of which have a cycle oi frequencymaterially lower than the cycle'of the alternating current, andpreferably so harmonized with relationto the Jfrequency of thealternating current that the vibration of the .armature corresponds to afactor of the cycle of the alternating current which energizes themagnet. l

Referring to the accompanying drawings, y

Fig. 1 vis a broken front elevation of a gonginstallation. employing amagnet in which my invention is embodied in one form; .i

Fig. 2 is a section on the line Q-2, Fig. 1; Y Fig-3 is a broken sideelevationof the -gon installation;

Fig. 4 is asection on the line 4.-.4, Fig. 1;

Whenalternating current is used to ener gizean electro-magnet, anoscillating eld is created which tends to impart to the armature avibratory movement'corresponding precisely to the frequency of thecurrent. .When the armature is associated with a gong hammer, this rapidoscillation causes the hammer to vibrate against the gong with a buzzingsound which is undesirable. It has consequently been common practice touse either direct currentwto energize the magnet, or so to arrange thearmature that but a single impact results when the magnet is energizedby an alternating current, as for example in the construction shown inIn co-pending application, Ser. No. 157,738.

Where a vibratory signal is desired, the result is accomplished with anD. C. mag'- net by means of a current interrupter of` desired frequency.I have now devised an' A. C. magnet which produces a substantiallyidenticallefeot by so arranging the armature thatthe cycle of itsvibrations, insteadl of corresponding to the cycle of the A. C.

l for the magnet, is lower than the latter.

ELECTROMAGNET.

Specification of Letters Patent. Patented Apl. 18, 1922.

191,7. Serial 179,709. I

Preferably the cycles have a predetermined harmonious relation whichinsures strokes of equal intensity for the hammer gong during themaintenance of the current 1n the magnet. i

Referring to the accompanying drawings in which I have embodied myinvention in an electric gong, the coils 10 and 11 are carried by a pairof non-magnetic brackets 12 and 13. A U-shaped core '1.4, referablylaminated, is so arranged that its branches 15 and 16 extend at theirfree ends beyond 'the coils, and are spaced apart by an air gap. Thearmature 17 works through this air gap at right angles to the plane ofthe branches 15 and 16 land is never in contact with the magnet poles.The armature is Y carried by a spring 18 mounted upon a carrier 19 whichmayA be secured in position in any suitable way, as, for instance, byriveting its base 2O to the bridge of the core 14. IVhen the magnet isused to operate. a gong hammer, as in the present instance, the hammer21 may be secured to the armature 17 by a bracket, such as 2Q. Both thecarrier` 19 and the spring 18 are preferably of non-magnetic material,such as brass. I so adjust the spring 18 that in its normal position ofrest, the armature 17 lies. toone side of the area of greatest magneticattraction between the poles 15 and 16. (See Fig. 2). In order toconcentrate the magneticxfeld and to localize the area of greatest`magnetic attraction` the pole pieces 15 and 16 are made V-shaped ontheir opposed faces with their-.apices 23 approaching each other asindicated. This is readily accomplished in laminated pole pieces byforming the free ends of the laminae with cross plates of differentlength, those at the central portion of the poles being greatest inlength', and those at the sides heilig least in length. Similarly, theopposite ends Q4 `of the armature 17 may be given a cor- `armaturetoward 'this position is so rapid,

however, that "its inertia carries it beyond this mid posltion.Moreover,-A the magnetic efforts are intermittent as a result of thenature otthe current employed. It desirable to so arrange the armaturethat the field is maintained at the moment the arma@ ture enters thearea of greatest magnetic effort, buty is interrupted as thc armaturepasses through the field so that its inertia carries it beyond theconcentrated field area before the succeeding current impulsereestablishes the field.` The stroke otl the armature is thus checked aslittle as is possible.

lt is also desirable to so space the gong from the magnet that after thehammer strikes the gong, its rebound is Substantially simultaneous witha current impulse, so that the armature mores backward not only underthe mechanical influence of' the rebound and the stress of its springsupport 1S, hut also under the pull of the magnetic field. These Vforcescarry the `armature through the concentrated magnetic field arca, thefield being again momentarily interrupted. By properly regulating thelength and strength ofthe spring 1S. and the weight and position of thehammer 2l and armature. the vibrations of the latter and its associatedmembers maybe so harmonized with the frequency of the alternatingcurrent that the cycle of armature vibrations has a predeterminedrelation to the cycle ot' the current pulsations. and is preferably soregulated that the number o't' strokes of the gong a factor of thenumber of pulsations or freqnency of the alternating current. Thus ifthe current has the usual,frequency of (it) the cycle or number ofstrokes maybe Q. il, i, 5, c, s. lo, ii, 2o, an, io. n must beunderstood that this harmonization of' the stroke cycles to the currentcycles is not essential to the desired operation of the armature, but itis j'n'eferred,` since by this arrangement a magnetic eflort is exertedupon the armature at ach end of its vibratory course as well asintermediate said ends. 'lrhis causes the strokes to be initiated with awell defined motion in each direction, and furthermore insures theirequality in duration. and in the strength of the impact upon the gong-acharacteristic which is not so pronounced if. for instance. a currentinipulse occurs just as the hammer is about to strike the gong thustending to halt it before impact. My experience has established that avibratory 'frequency ot 2O for the armature gives a mostsatisfactoryaction for the gong hammer.

The particular housing of the magnet and its associated parts may bemodified in any desired fashion, l have shown a convenient arrangementwhich is of advantage in making the installation since it permits thewiring for the gongs to he installed during the construction of thebuilding. while the gongs and their associated magnets may be installedlater after the huildin'g operations vhave been completed.` Thispreserves vthe gong and its mechanism from accumulating dirt during thebuilding operations and protects the parts from accidental injury. Tothis end, l have provided an outlet box 25 to which the signal wire maybe led through conduits QG and 2T. Upon one wall of the box 25 ismounted-an insulating base 28 carrying a pair ot' connecting plates 29and :30. to which the incoming and outgoing wires may be connected atthe time of the conduit installation. The brackets 1Q and 13, carryingthe magnet coils l() and lil may be mounted within a casing 3l castintegral with the arm 32 on which the gong 33 is mounted. The stem ofthe gong hammer 2l yibrates in a slot 34; formed in the lasing 31',while a supplemental hood B5 is secured to the main casing to protectthe exposed hammer head from injury. An apron 86 depends from the casing3l and surrounds the magnet ll which lies below the lower margin of thecasing. ln assembled position. the apron 36 extends into the outlet` boxt0 one side of the insulating block Q8. Aper tures 3T in the apronpermit the connecting wires 38 to be led from the terminal plates 29 and3l) to the magnet coils. A guard B9 lmounted upon one of the branches ofthe magnet core extends into the path of the armatuie 17 to preventexcessive vila-ation thereof.

Various modifications in detail of construction will readily occur tothose skilled in the art without departing from what I claim as myinvention.

l claim :M

l. An, alternating current electro-magnet comprising spaced pole pieces,an armature vibrating across the lines of force between said polepieces, and means constraining said aru'iature, under the influence ofthe magnetic field, to a frequency of vibration constituting asub-1nultiple ot the frequency ot the alternating current whichenergizes the magnet.

2. rin alternating current electro-magnet comprising pole pieces"ikshaped to afford a concentrated magnetic field and an armaturevibrating through the concentrated field across the lines of. force andback and forth past the point ot' greatest-attraction when the magnet isenergized.

Si. .in alternating current electro-magnet comprising a pair of polepieces having" their opposed faces V-shaped to afford a concentratedmagnetic field and an armature vibrating through said field past theapices of said pole pieces.

f-l. An alternating current electro-magnet comprising pole pieces spacedapart and an armature vibrating through the air, gap between the polesacross the lines of force, said armature having the ends adjacent thepole pieces V-sliaped for the purpose specified.

5. in alternating current electro-magnet comprising a pair of polepieces having4 In an alternating current electro-mag-v net, an armature,and a spring-actuated support therefor constraining said armature, underthe influence of the magnetic field, to a frequency of vibration lowerthan the frequency of the alternating current energizing the magnet.

T. In an alternating current electro-rnagnet, an armature, and aresilient support therefor constraining said armature, under theinfluence of the magnetic field, to a frequency of vibration lower thanthe frequency of the. alternating current energia? ing the magnet.

.5. In an alternating' current electro-magnet, spaced pole piecesV-shaped to afford a concentrated magnetic field therebetween, anarmature normally lying te one side of the area of greatestconcentration of the lines of force, but arranged to Vibrate'a'cross thelines of force of said magnetic field, and means constraining saidarmature, under the influence of the magnetic'field, to a frequency ofvibration lower than the frequency of the alternatingvcurrent energizingthe magnet. Y

9. In an alternating current electromagnet, spaced pole pieces, anarmature vibrat ing across the lines of force between said pole pieces,and means constraining said armature, under the influence of saidmagnetic field, to a frequency of vibration lower than but harmoniouswith the frequency of the magnet-energizing current.

10. In an alternating current electro-magnet, spaced pole pieces, anarmature vibrating across the lines of force between said pole pieces,and means constraining said armature, under the infiuence of Saidmagnetic field, to a frequency of vibration lower than that of themagnet-energizing current but constituting a factor of its frequency.

11. In an alternating current electro-magnet a pair of laminated poleshaving their central laminae longer than the marginal laminas to affordopposed V-shaped facesse` curing a concentrated magnetic field.

1Q. In an alternating current electro-mag. net a laminated -armaturehaving its central laminas longer than its outer laminas to produceV-shaped ends for the 'purpose described.

13. In an alternating current electro-magnet, a pair of spaced poleslhaving opposed V-shaped faces to 'afford a concentrated field, and anarmature having V-shaped endsvibrating through the air. gap between thepoles across the linesof force.

In testimony whereof I have signed'my .name to this specification.

i oHAELEs E. AVERY.

Certificate of Correction.

It isiv hereby .certified that in Letters Patent No. 1,413,374, grantedApril 18,

1922, vupon the application of Charles E. Avery, of Trenton, New Jersey,for an improvement in Electromagnets, an error appears in the printedspecification requiring correction asl follows: Page 3,.line4 7, claim5, for U-shaped read V-shaped; and that the said Letters Patent shouldybedreadv with this correction therein that the same may conform to therecord of the ycase in the Patent Ofice.

vSigned and sealed this 9th day of May, A. D., 1922.

[SEAL] KARL FENNING,

Acting Commissioner of Patents.`

